1/4 Wave Theories - What now?

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From:  D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent:  Monday, June 01, 1998 12:30 PM
To:  Tesla List
Subject:  Re: 1/4 Wave Theories - What now?

to: Terry

I think most of the capacitance is turn to turn but it would be very easy
to test your theory.  Measure the cap of a secondary inductor and then
elevate it approx 25-30 feet above ground (in a sense isolate it from any
nearby ground plane) and then measure the capacitance again.  If the cap is
turn to ground the value should diminish considerably --- if the cap is
turn to turn as I suspect the value should not change very much.  You could
elevate it on some plastic spools, a wooden pole, or even a bunch of
cardboard boxes stack up high.  A simple test that will validate your
theory or invalidate it.

DR.RESONANCE-at-next-wave-dot-net

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> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: 1/4 Wave Theories - What now?
> Date: Sunday, May 31, 1998 11:21 PM
>
>
> ----------
> From:  terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
> Sent:  Saturday, May 30, 1998 3:09 PM
> To:  Tesla List
> Subject:  1/4 Wave Theories - What now?
>
> Antonio and All,
>
> Here is my pet theory about resonances capacitances and such.
>
>         I believe that the self capacitance is the capacitance of the
> windings to ground.  Each turn has a capacitance to ground along the
length
> of the coil.  Each capacitance is separated from the rest by some
inductance
> depending on where they are located.  This produces all kinds of local RC
> networks.  As you tune around the coil you happen upon points were the
> resonances add up and cause a peaking effect.  This accounts for the
little
> resonance points we see during tuning.  The real key here is that all the
> currents seem to be in phase along the coil.  No big standing waves as we
> have all thought in the past.
>         I should also point out that there is a voltage node at the base
of
> the secondary simply because it is grounded there :-)  This zero voltage
> point has nothing to do with any standing waves.  The currents in my
tests
> clearly show that the top and bottom secondary currents are in phase.  Of
> course, the current and voltage are 90 out of phase as in any LC network.
>         The current at the top of the coil is about 65% of the current at
> the base.  I believe this is due to the current splitting between the top
> terminal and the self capacitance.
>
>         This is all rather new so there are still details to be worked
out.
> I have not seen any big problems with this so far.
>
> Regards,
>
>         Terry Fritz
>
>
>
> At 11:24 PM 5/29/98 -0500, you wrote:
> >
> >----------
> >From:  Antonio Carlos M. de Queiroz [SMTP:acmq-at-compuland-dot-com.br]
> >Sent:  Friday, May 29, 1998 8:12 PM
> >To:  Tesla List
> >Subject:  Re: 1/4 Wave Theories - Trash Them!
> >
> >Terry Fritz wrote:
> >
> >> These measurements indicate that the secondary is
> >> acting as a simple lumped inductor.  There appears to be no 1/4 wave
effect.
> >> The currents are in phase.  It appears that the 1/4 wave theory of
Tesla
> >> coil operation is incorrect.  Also, the top terminal appears to be
acting as
> >> a simple capacitor in parallel with the coil's self capacitance.  A
model
> >> for this behavior is presented.
> >
> >If the top capacitance is significantly greater than the
"self-capacitance",
> >the behavior is very precisely the one of a lumped circuit. Without any
top
> >capacitance, 1/4 wave resonance is a better model, but the difference
between
> >an open-ended (rather peculiar) transmission line and a lumped circuit
is
> >negligible, at that first resonance. To verify clearly that a resonator
is
> >a transmission line, try to find other resonances above the main
resonance.
> >There should be another at a frequency that is between two and three
times
> the main
> >resonance without top load (f0), depending on the top load capacitance,
and
> others
> >above, separated by somewhat less than 2f0.
> >I can easily count more than ten in a test coil.
> >
> >(I will be out of the list for the next week)
> >
> >Antonio Carlos M. de Queiroz
> >
> >
> >
> >
>

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